What is ASME B16.34 and why is it important for valves?
ASME B16.34 is a standard for valves flanged, threaded, and welding end that was developed by the American Society of Mechanical Engineers (ASME). It covers pressure-temperature ratings, dimensions, tolerances, materials, nondestructive examination requirements, testing, and marking for cast, forged, and fabricated valves of various types and alloys. The standard also includes wafer or flangeless valves that are installed between flanges or against a flange.
ASME B16.34 is important for valves because it provides a common basis for design, manufacture, inspection, and testing of valves. It also ensures compatibility and interchangeability of valves from different manufacturers and sources. By following the standard, valve users can be assured of the quality and performance of their valves in various applications and conditions.Types of valves covered by ASME B16.34
ASME B16.34 covers various types of valves that have flanged, threaded, or welding end connections. These include gate, globe, plug, ball, check, and butterfly valves. The standard also covers wafer or flangeless valves that are installed between flanges or against a flange. The valves can be cast, forged, or fabricated from different materials and alloys.
The standard specifies the pressure-temperature ratings for each type of valve and material group. The ratings are based on the valve design, material properties, and service conditions. The standard also provides tables and formulas for calculating the pressure-temperature ratings for intermediate temperatures and special class valves.
Nondestructive examination and testing requirements for ASME B16.34 valves
ASME B16.34 requires that valves undergo nondestructive examination (NDE) and testing to ensure their quality and performance. The NDE methods include visual examination, radiographic examination, magnetic particle examination, liquid penetrant examination, ultrasonic examination, and hardness testing. The standard specifies the acceptance criteria and frequency of NDE for each type of valve and material group.
The testing methods include shell test, backseat test, low-pressure closure test, high-pressure closure test, and supplementary tests. The standard specifies the test pressures, durations, mediums, and leakage rates for each type of test. The standard also provides guidance on how to conduct the tests and how to mark the valves after testing.Marking requirements for ASME B16.34 valves
ASME B16.34 requires that valves be marked with certain information to identify their characteristics and origin. The marking must be legible, durable, and visible after installation. The marking can be done by stamping, casting, forging, etching, or other methods approved by the manufacturer.
The ASME B16.34 marking specification complies with Manufacturers Standardization Society (MSS) SP-25 standard-marking system for valves, fittings, flanges and unions. The minimum requirements for marking valves are:
Name of manufacturer
Materials of body, bonnets, cover plates
Size (NPS or DN)
ASME B16.34 designation
Flow direction (for check valves)
Year of manufacture
Serial number (optional)
The standard also provides additional marking requirements for special class valves, cryogenic valves, wafer or flangeless valves, and valves with supplementary NDE or testing. a474f39169